Scope of Dendrology in Forest Botany, 231 



compass four distinct subdivisions may to-day be distinguished. 



Systematic dendrology dealing witii such characteristics' of 

 trees, in their summer and winter conditions, as are of practical 

 service in field identification. The distinctively winter charac- 

 ters are usually not dwelt upon in botanical field courses. All 

 this differs, too, from the taxonomic study of botanists in being 

 confined exclusively to those characteristics that are of service in 

 the field. In almost any botanical manual, except to some extent 

 in the newer ones for trees designed along forestry lines, half 

 or more of the taxonomic characters mentioned are not used in 

 systematic dendrology, whose sole purpose is to afford a field 

 basis for distinguishing one tree species from another, and not 

 to present a complete taxonomic scheme. So much of botanical 

 taxonomy as the forestry student requires belongs to his botanical 

 study proper and not to his dendrological work in forest botany. 

 Dendrology, in its four subdivisions as here detailed, covers a 

 very wide range. The practical needs are for drawing its boun- 

 daries closer rather than for extending them. 



Geographic dendrology, or the ranges of tree species. 



Biologic dendrology, or the systematic consideration of those 

 characteristics of tree species that relate to their life-histories, 

 pursued along non-ecological lines. This part of the subject 

 verges upon the domain of silvics. Biologic dendrology is, how- 

 ever, systematic, that is to say rather a recital of the facts in- 

 volved in the climatic requirements of the species', their edaphic 

 needs, habits of growth, tolerance, reproduction, and so on, than 

 an analytical exploration of the ecological problems embraced 

 within these matters, which properly belongs to the subjects of 

 forest-ecology and silvics. Biologic dendrology may, indeed, 

 fairly be thought of as preliminary to this. Quite aside from this' 

 aspect of the subject as one preliminary to the study of silvics 

 is its important aspect of furnishing the student of forestry with 

 information that is indispensable to him from almost the be- 

 ginning of his study of forestry, a selected array of facts that> 

 he would best get first in clear-cut, systematic form, before in- 

 volving himself in the far more difficult considerations of their 

 ecological meanings. This has been recognized in educational 

 practice to the extent that so far in the teaching of forestry in 

 this country it has been largely biologic dendrology that has been 

 taught rather than silvics, whatever titles may have appeared in 



